1. Field of the Invention
This invention relates to an electroless nickel plating bath not employing harmful metal species, a stabilizer for the electroless nickel plating bath, a method for electroless nickel plating, and to a method for managing the electroless nickel plating bath.
2. Description of Related Art
The electroless nickel plating yields high film characteristics and a sufficiently uniform precipitation characteristic, and hence has been in extensive use. Among a variety of electroless nickel plating baths used for electroless nickel plating, there are known, for example, a plating bath that uses sodium hypophosphite, a phosphorus compound, as a reducing agent (a Ni—P bath), and a plating bath that uses dimethylamino borane (DMAB), a boron compound, as a reducing agent (a Ni—B bath). The electroless nickel plating bath is referred to below simply as a plating bath.
The electroless nickel plating suffers from problems such as a phenomenon of sudden abnormal precipitation ascribable to active hydrogen generated by oxidation of a reducing agent, that is, decomposition of a plating bath. To prevent such decomposition of the plating bath to enable the plating bath to be used for a prolonged period of time, a stabilizer is usually added to the plating bath. Harmful metal species, such as lead or bismuth, are known to be effective as the stabilizer for the electroless nickel plating (see Patent Publication 1, for example).
[Patent Publication 1] Japanese Laid-Open Patent Publication 2007-154223